There are two general challenges in nanoscience and nanotechnology. One challenge is to fabricate nanoarchitechtures, such as nano-electrodes, diodes, and resistors, in less than 10 nanometer (nm) resolution. The second challenge is to assemble nanostructures into patterns, such as nanorod or nanodisk arrays, in a regular arrangement, with precise control and high throughput (Gates et al., Chem Rev, 105, 1171, 2005; Ieong, et al., Science, 306, 2057, 2004).
Several routes for synthesizing nanostructures have been developed. Many of these new structures have interesting electronic, optical, and chemical sensor properties that derive from their size, composition, and shape (Iijima et al., Nature, 363, 603, 1993; Thess et al., Science, 273, 483, 1996; Heath et al, Chem Phys Lett, 208, 263, 1993; Morales et al, Science, 279, 208, 1998; Martin, Science, 266, 1961, 1994; Martin, Acc Chem Res, 28, 61, 1995; Routkevitch et al, Chem Phys, 210, 343, 1996). However, methods of synthesizing multicomponent materials made from both organic and inorganic materials are few (Gudiksen et al, Nature, 415, 617, 2002; Lee et al, Angew Chem Int Ed, 43, 3048, 2004; Kovtyukhova et al, J Phys Chem B, 105, 8762, 2001; Pena et al, J Phys Chem B, 106, 7458, 2002; Park et al, Science, 303, 348, 2004; Nicewarner-Pena et al; Science, 294, 137, 2001).
Porous templates offer an ability to routinely generate such multicomponent materials through two distinct methods. Both rely on the use of electrochemistry to generate an initial segment of metal from a plating solution. However, one method utilizes layer-by-layer chemisorption processes (Kovtyukhova et al, J Phys Chem B, 105, 8762, 2001), to build organic segments on top of a preformed metal segment, while the second method utilizes conducting polymer monomers combined with an appropriately applied potential to polymerize the monomer within the template at the metal segment solution interface (Park et al, Science, 303, 348, 2004). An advantage of the latter approach is that it provides excellent control over the segment length of the metal and organic regions of the structure, simply by controlling the number of Coulombs (C) that are passed in the experiment. This disclosure provides another approach, based upon this synthetic strategy, for preparing hybrid multicomponent (e.g., organic-inorganic or metal-metal) nanorods having electronic properties derived from their compositions, wherein the spatial distribution of the different compositional segments can be precisely controlled.
Lithography is a powerful way of processing substrates for use in many practical applications, including semiconductor and optical industries. Many methods of printing structures on flat substrates are known, and some methods for printing on large curved architectures are also known (Melosh et al, Science, 300, 112, 2003; Chou et al, Science, 272, 85, 1996; Xia et al, Chem. Rev., 99, 1823, 1999; Erhardt et al, Chem. Mater., 12, 3306, 2000).
Fabricating features on any of these substrates at the micron to macroscopic length scale is now routine, and with advances in nanotechnology, it is possible to print a limited set of structures made from a variety of hard and soft materials with size control of features down to ten nanometers (Crommie et al, Science, 262, 218, 1993 and Hua et al, Nano Lett., 4, 2467, 2004). Although they have many attributes and capabilities, nanolithographic techniques, such as electron beam lithography, dip-pen nanolithography (DPN), focused ion-beam lithography, and nanoimprint lithography, are limited with respect to throughput, materials compatibility, resolution, and/or cost (Gates et al, Chem. Rev., 105, 1171, 2005). For example, the field of nanoelectronics relies upon the ability to fabricate and functionalize less than 20 nm, i.e., sub-20 nm, electrode gaps for precise electrical measurements on nanomaterials. Fabricating such structures is far from routine and often involves low-yielding, imprecise, and difficult-to-control procedures, such as break junction techniques and gap narrowing by electroplating (Reed et al, Science, 278, 252, 1997; Park et al, App Phys Lett, 75, 301, 1999; Li et al, App Phys Lett, 77, 3995, 2000; Xiang et al, Angew Chem Int Ed, 44, 1265, 2005). Other methods of preparing nanorods having different segments are disclosed in U.S. Patent Application Publication Nos. 2003/0209427, 2002/0104762 and 2004/0209376.
The present invention is directed to resistors and diodes composed of nanorods produced in a high-throughput procedure that allows for the systematic creation of large quantities of identical nanorods in an aligned array. These nanorods are then facilely used as diodes or resistors; depending upon the components of the nanorod and their electronic properties. The present invention provides a method of generating assembled nanorod structures with control over both the length of, the distance, between, and the electronic properties of rods, allowing for the formation of novel resistors and diodes.
The present invention is also directed to a new, general, and relatively high throughput procedure for lithographically processing one-dimensional arrays of nanodisks in which the sizes of the gaps between disks can be controlled down to the 5 nm length scale. This procedure, termed on-wire lithography (OWL), combines advances in template directed synthesis of nanowires with electrochemical deposition and wet-chemical etching, and allows the routine fabrication of architectures previously considered difficult, if not impossible, to manufacture via any known lithographic methodology. The present invention provides a method, through OWL, of generating one-dimensionally assembled nanorod structures and nanodisk arrays, with control over both the length of, and the distance between, rods or disks respectively.